Purpose :
Myopia is increasing all over the world, and treatment options to reduce myopia progression are currently under development. To optimize treatment strategies, in depth knowledge on the natural course of myopia progression is required. The aim of this study is to describe myopia progression trajectories and the association between age of onset and final refractive error in a cohort in European children and teenagers.

Methods :
The Drentse Refractive Error and Myopia Study (DREAMS) acquired retrospective data from 1988 onwards from a database of 14 practices of a dispensing optician in the North of the Netherlands. Subjects were eligible if they visited the optician before the age of 25 years and had at least two measurements of refractive error with an interval of a year or more. Myopia onset was defined as first pair of glasses with a spherical equivalent (SphE) between -0.5 and -2.5 D. Differences in SphE between age of onset groups were tested with ANOVA and chi-square.

Results :
A total of 2189 subjects had at least two measurements with a median follow up time of 4 years (range 1 – 22 years). Subjects with a myopia onset before the age of 10 had a significant more negative mean SphE (-4.72D; SD 1.61) at the age of 25 than subjects with a later myopia onset (P <0.001, Figure 1). In the total cohort, high myopia developed in 184 (8.4%) subjects, but significantly more in those with myopia onset before the age of ten, (26% vs 1%, P <0.001) . Mean annual progression was the highest before the age of 10 and reduced after 15 years of age (-0.39D/year ±0.33 vs. -0.11D/year ±0.20).

Conclusions :
Early age of myopia onset and fast progression rates of SphE are important determinants of high myopia at adult age. By the age of 25, 20% of subjects who had developed myopia before the age of 10 had high myopia. Progression rates decline with age similarly in low and high myopia groups. Our risk estimates and progression rates can be used as reference data when treating European children for myopia progression.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.